Welterweight titleholder Kell Brook was not joking around when he said he wanted to return to 147 pounds and defend his belt against dangerous mandatory challenger Errol Spence Jr.

A purse bid for the fight, which was scheduled to take place Tuesday afternoon at IBF headquarters in Springfield, New Jersey, was postponed on Monday for one week at the request of both camps.

Matchroom Boxing promoter Eddie Hearn, who represents Brook, has been locked in negotiations with TGB Promotions boss Tom Brown, who is representing Spence. They have made enough progress that both sides felt like it was better to seek a postponement of the purse bid rather than have to hurry through the rest of the talks to have a deal done by Tuesday afternoon.

Welterweight titleholder Kell Brook had surgery to repair an eye injury suffered in a September fight. Ethan Miller/Getty Images

"We are close to a deal and both sides have requested an extension of a week," Hearn told ESPN.

Brown told ESPN, "We are getting close to making a deal. This is a big fight and we hope to get it done before next week's rescheduled purse bid."

The IBF granted the extension, sending a letter to all IBF-registered promoters on Monday to announce the delay.

IBF president Daryl Peoples said in the letter, a copy of which was obtained by ESPN, that the organization agreed to grant the request and "therefore, the IBF will call for purse bids to be held in these offices on Tuesday, February 14, 2017." Bids must be submitted by 11:45 a.m. ET with the sealed bids to be opened at noon ET in the event Hearn and Brown do not reach an agreement by then. If the bid procedure takes place, the promoter with the highest bid will gain promotional control of the fight and can select when and where it will take place as well as control all other logistics.

At the time of the bid, promoters interested in participating must pay the IBF a non-refundable fee of $5,000 along with a check for 10 percent of their bid amount with another 10 percent of the winning bid five days later. However, Hearn and Brown appear on their way to getting a deal done that will result in the cancellation of the purse bid altogether.

Hearn said the sides have not yet agreed on a site but that they hope to put it on in late May. The fight almost certainly would generate much more money if it were to take place in Brook's native England, where he is a big draw.

The 30-year-old Brook (36-1, 25 KOs) could not get a big name opponent to fight him so he moved up two weight classes to middleweight and challenged unified titleholder Gennady Golovkin in September at the sold-out 02 Arena in London. It was a major event and an action-packed fight, but Golovkin broke the orbital bone around Brook's right eye in a fifth-round knockout victory. Brook later had surgery to repair the injury and has struggled with what his next move should be.

There was the prospect of a huge all-British fight with former unified junior welterweight titlist Amir Khan in a match British fans have wanted for years. But Khan's demands, including 70 percent of the money, killed the prospect of the fight.

Brook struggles to make 147 pounds, so he also considered fighting as a 154-pound junior middleweight, but there was no obvious major fight for him in the division. More significantly, Brook does not want to give up his world title, which he has defended three times since winning it by majority decision from Shawn Porter in August 2014. Brook's mandatory defense against Spence, 27, of DeSoto, Texas, is due and if Brook took any other fight he would have to relinquish the title or would be stripped.

"He doesn't want to vacate," Hearn said.

Indeed, Brook, who has recovered from the injury, was struggling badly with what he wanted to do when he spoke to ESPN in New York last month.

"I know I have a mandatory with Errol Spence. He's a very talented fighter but not really heard of in the U.K. or even America but we all know he can fight," Brook said. "It's hard to get up for guys like this because he doesn't have the name yet. I want the big money fights if I'm going to make 147 pounds. We're reaching the deadline. I have another month. Even if we can make the big fights with [Manny] Pacquiao or Khan, I'm in a situation where I still might have to defend against Spence because I don't want to lose my title without losing it in the ring."

Spence (21-0, 18 KOs), the 2015 ESPN.com prospect of the year and one of the hottest contenders in boxing, is viewed by most as an extremely difficult defense for Brook. The 2012 U.S. Olympian pummeled former junior welterweight titlist Chris Algieri in a fifth-round knockout in April before scoring a similarly dominant sixth-round knockout of Italy's Leonard Bundu in August in a world title elimination fight that made him the mandatory challenger for Brook's title.